Information relevant to the present disclosure may be found in Won, U S. Pat. No. 4.690.825 (issued Sep. 1, 1987). Woo. U.S. Pat. No. 4,514,461 (Apr. 30, 1985). and pending U S. patent applications Ser. No. 07/091,641 (filed Aug. 31, 1987) abandoned and Ser. No. 07/197,375 (filed May 23, 1988) now U.S. Pat. No. 4,873,091 both commonly assaigned herewith.
The use of fabrics, sponges, and other porous, absorbent or intersticed materials as a means for retaining functional substances is known The functional substances may range widely in character. and serve a wide range of purposes, including therapeutic, cosmetic. hygienic, and preventive functions. Examples of products embodying such materials are personal care products, cosmetics, toiletries, fragrances, pharmaceutical products, and household and industrial products, in either permanent, semi-permanent or disposable form.
An important feature of many such products is their ability to extend their utility over a long period of time by retaining sizeable quantities of the functional ingredients while exposing only a portion of them to the surroundings where they are available for use. Control of the release rate is achieved in a variety of ways. including diffusion through the interstitial network, forcing the ingredient to the surface by compression of the interstices, and rupture of internal bubbles or cells in the matrix material.
These mechanisms rely considerably on the structure of the matrix material itself, and this places limitations on the selection of the material as well as its properties.